We studied the effect of gastric bypass surgery, an efficient method to induce weight loss in morbid obesity, on gut microbiota and potential associations with gene expression in fat tissue. We found that gastric bypass surgery was associated with increases in microbial richness and that these changes were in turn associated with a variety of gene expression changes in fat tissue. The resulting publication appeared in the American Journal of Clinical Nutrition.



Roux-en-Y gastric bypass (RYGB) surgery is one of the most efficient procedures for treating morbid obesity and results in weight-loss and improvements in metabolism and inflammation.


We examined the impact of RYGB on modifications of gut microbiota and its potential associations with changes in gene expression in white adipose tissue (WAT).


Gut microbiota were profiled from fecal samples by using pyrosequencing in morbidly obese individuals, explored before (0 mo), 3 mo after, and 6 mo after RYGB. WAT gene expression was studied at 0 and 3 mo. We explored associations between microbial genera and differentially expressed genes in WAT and clinical markers.


The richness of gut microbiota increased after RYGB; 37% of increased bacteria belonged to Proteobacteria. The associations between gut microbiota composition and WAT gene expression increased after RYGB. Fourteen discriminant bacterial genera (7 were dominant and 7 were subdominant) and 202 WAT genes changed after RYGB. Variations in bacterial genera correlated with changes in both clinical phenotype and adipose tissue gene expression. Some genes encode metabolic and inflammatory genes. Almost half of the correlations were independent of the change in calorie intake.


These results show an increase in gut microbiota richness and in the number of associations between gut microbiota and WAT genes after RYGB in obesity. Variations of gut microbiota were associated with changes in WAT gene expression. These findings stimulate deeper explorations of the mechanisms linking gut microbiome and WAT pathological alterations in human obesity and its changes after weight loss.


Kong LC1, Tap J, Aron-Wisnewsky J, Pelloux V, Basdevant A, Bouillot JL, Zucker JD, Doré J, Clément K.

Journal and Citation

American Journal of Clinical Nutrition 98(1): 16-24 (29th May 2013)

Received 15th January 2013 | Accepted for publication 8th April 2013 | First published online 29th May 2013


Link: http://ajcn.nutrition.org/content/98/1/16.long

Associated link: http://ajcn.nutrition.org/content/99/3/649.2.long

Associated link: http://ajcn.nutrition.org/content/99/3/650.long

Press coverage: http://www.nutraingredients-usa.com/Research/Weight-loss-leads-to-significant-gut-microbiota-changes


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